So now I started again. Loaded G3F unmodified - just the base figure. Loaded Cailin dress and set it to base resolution then decimated by 50%. Chose a different sitting pose. Ran VWD with all the usual (as per Biscuits) parameters. The dress did not move during the simulation. There was some odd activity in the groin area but no draping.

By the way - I'm doing a static simulation. This is not for an animation and it is a fully rigged dress so, as I understand it, static is what I should be using.